Sugar cane (Saccharum spp.) is an important source of raw material for sugar industries and for allied industries involved in the production of such products as alcohol, acetic acid, butanol, paper, plywood, industrial enzymes, and animal feed. These industries seek to improve sugar cane by introducing heterologous polynucleotides that confer desirable characteristics or traits.
Agrobacterium tumefaciens is a soil-borne pathogen that is widely used to introduce heterologous polynucleotides into plant cells, including plant cells from sugar cane. A. tumefaciens transfers a particular polynucleotide segment of a tumor-inducing (Ti) plasmid into the nucleus of infected host cells, which subsequently stably integrates into the host's genome. Advantageously, heterologous polynucleotides can be placed between the borders of the Ti plasmid and transferred to plant cells.
Although Agrobacterium-mediated transformation has been used for genetic manipulation of sugar cane, efficiency and reproducibility of the available methodologies continue to be a challenge. In fact, A. tumefaciens induces necrosis in cultured, transformed sugar cane tissue, with a resultant low transformation frequency (Arencibia et al. (1998) Transgenic Res. 7:123-222; Enriquez-Obregón et al. (1997) Biotecnologia Aplicada 14:169-174; and de la Riva et al. (1998) Electron. J. Biotechno. 1:118-133).
Because of the importance of manipulating sugar cane for improved characteristics (e.g., increased resistance to biotic or abiotic stresses, or improved production), there is a need for additional methods that advantageously increase the efficiency of Agrobacterium-mediated transformation of this important agricultural crop.
Accordingly, the present invention overcomes the deficiencies in the art by providing methods of Agrobacterium-mediated transformation of sugar cane and other important plants that result in greater transformation efficiencies.